S. Darzens

The creep mechanism of ceramic matrix composites at low temperature and stress, by a material science approach

Abstract This paper deals with the creep mechanism for ceramic matrix composites reinforced by long ceramic fibers in a ceramic or glass-ceramic matrix, tested at low stresses (

Understanding of the creep behavior of SiCf-SiBC composites

Abstract This paper deals with some creep results on a new generation of a ceramic matrix composite with a self-healing matrix. This investigation is based on the creep curves, the observation of damages and their quantification by image analysis, and the application of the damage mechanics approach. The results obtained herein illustrate the concept of the damage-creep mechanism.

Microstructural investigation of interfaces in CMCs

This paper is focused on the importance of pyrocarbon interfaces in two types of ceramic matrix composites (C f -SiC and Sic f -SiBC), during creep tests under argon. The development of micromechanisms which consume energy and then allow a damage tolerance, depends on the morphology of the fiber/matrix interphase, which has been investigated by TEM and HRTEM.

Creep Behavior and Mechanism for CMCs with Continuous Ceramic Fibers

This paper gives an overview on the creep behavior and mechanism of some CMCs, with a SiC ceramic matrix, such as Cf-SiC, SiCf-SiC and SiCf-SiBC. Tensile creep tests were conducted under argon and air in order to have the influence of the environmental conditions on the macroscopical mechanical response. Nevertheless, multi-scale and multi-technique approaches were required to identify and quantify mechanism(s) which is (are) involved in the creep behavior. The initiation and propagation of damages which are occurring under high stress and temperature conditions were investigated at mesoscopic, microscopic and nanoscopic scales using SEM, TEM and HREM, in order to identify the mechanism(s) involved at each scale. Automatic image analysis was used in order to quantify the evolution of some damage morphological parameters. The macroscopical creep behavior has been investigated through a damage mechanics approach which seems to be the most promising route. A good correlation was found between the kinetics of the damage mechanisms and the creep behavior. For such ceramic matrix composites, the governing mechanism is a damage-creep one, with an additional delay effect due to formation of a glass when tests are performed under air.

Damage Development Upon Creep Test in Ceramic Matrix Composites

Microstructural investigations performed in parallel with creep experiments have evidenced the occurrence of damage processes involved in the global creep mechanism of ceramic matrix composites. A qualitative evaluation, through the damage mechanics, has confirmed such a damage accumulation. Therefore, a new concept has been proposed and is illustrated as a particular mechanism responsible for the creep strain of these composites: the damage-creep mechanism. On a way towards modeling of the creep behavior via a quantitative analysis of the damage development, this paper reviews the damage processes encountered in the creep study of different CMCs.